There is a defogger relay that sounds like it is not working. Here is a wiring diagrams and a guide to confirm the issue.
The connectors for rear window defrosters are traditionally either at the bottom of the grid on both sides, top of the grid, or on the driver's side of the grid, visible just by looking at the rear window from inside the vehicle.
Oh, and make sure there is power on both sides of the switch when the switch is enabled. The switch could be defective internally, allowing the light to turn on, but not passing power out of the switch.
Check out the diagrams (Below)
Please let us know what you find. We are interested to see what it is.
Images (Click to enlarge)
Thursday, September 29th, 2011 AT 8:52 PM